Storage unit



April 23, 1970 R. G. HAGENAUER ETAL 3,508,881

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C 100 E :Lf/2] Tij] lf3 112 3 96] i: uu- 57:?. yy Q6 95 57 ATMos rH Ew;117 :L 117 RE H E ATS Il q 98H3 /n :P j? 98 United States Patent O3,508,881 STORAGE UNIT Richard G. Hagenauer, Southfield, Mich., Jack I.Anderson, Salinas, Calif., and Marvin A. Fuller, Benton Harbor, andAlexander L. Reiter, St. Joseph, Mich., assignors to WhirlpoolCorporation, a corporation of Delaware Original application Mar. 9,1964, Ser. No. 350,205, now Patent No. 3,307,618, dated Mar. 7, 1967.lDivided and this application Dec. 1, 1966, Ser. No. 598,255

Int. Cl. B01j 7/00; F26b 2.1/06; A23b 7/00 U.S. Cl. 23--281 2 ClaimsABSTRACT OF THE DISCLOSURE Fluid circuitry and atmosphere control systemfor automatically maintaining preselected levels of oxygen, carbondioxide, nitrogen and moisture in the atmosphere of a storage containerfor plant and animal materials.

This application is a division of our copending application Ser. No.350,205, led Mar. 9, 1964 which has matured in U.S. Patent No.3,307,618, on Mar. 7, 1967.

This invention relates to a storage unit for storing perishable animaland plant materials and to controls therefor.

In Bedrosian et al. Patent 3,102,777 there is disclosed and claimed anapparatus and method of preserving animal and plant materials in whichthe materials are subjected to a storage atmosphere containing oxygenand car- -bon dioxide in controlled quantities and in which thematerials may be maintained at a desired storage temperature dependingupon the type of material being stored.

In the copending application of Fuller et al. Ser. No. 316,991, nowPatent No. 3,183,683, led Oct. 17, 1963, there is disclosed and claimeda container which may be fixed or portable in which the materials may bestored. Both this application and the above patent are assigned to thesame assignee as is the present application.

The invention disclosed and claimed herein may be embodied in acontainer or storage unit as disclosed and claimed in the above Fulleret al. application.

As is explained in the above Bedrosian et al. Patent No. 3,102,777, thedegradation of stored animal and plant materials can be expressed by thefollowing approximate respiratory change equation:

In this equation which expreses the chemical reactions involved, (CH2O)represents a carbohydrate molecule that is destroyed during thedegration or deterioration process w-ith n being a whole numberdependent upon the size of the molecule, with the size of the molecule,of course, depending upon the number of recurring CH2O units present.The practical lower limit of n is, of course 6 and in this case thecarbohydrate molecule would be that of a simple sugar. For more complexmolecules n could be extremely large such as 1,000,000 or more. However,in every instance one molecule of oxygen is consumed for each @H2O unitin the carbohydrate with the production of one molecule of carbondioxide and one molecule of ice water. The carbohydrates are eitherpresent as such in the plant materials and microorganisms or may beproduced as end products from other substances such as proteins andfats. In any event, the deterioration changes on storage of both animaland plant materials in the presence of oxygen such as the oxygen ofnormal air is expressed by the above chemical reaction equation.

The present invention provides apparatus for regulating and maintainingthe amount of oxygen and carbon dioxide in the storage atmosphere sothat the above equation can be materially slowed to increase the life ofthe stored materials. In addition, the apparatus of this inventionpermits control of the humidity and temperature conditions within thestorage space.

One of the features of this invention is to provide an improvedapparatus for storing for a period of time perishable animal and plantmaterials having improved means for controlling the environment withinthe container including the contents of the storage atmosphere, thehumidity conditions and the temperature conditions, either individuallyor in combinations.

Other features and advantages of the invention will be apparent from thefollowing description of one embodiment thereof taken in conjunctionwith the accompanying drawings. Of the drawings:

FIGURE 1 is a semi-schematic cross sectional elevational view of astorage container embodying the invention together with environmentalcontrols therefor.

FIGURES 2 and 3 together constitute an across the line circuit diagramfor the electrical portions of the apparatus.

FIGURES 2 and 3 together constitute a key diagram for the circuit ofFIGURES 2 and 3.

FIGURE 4 is a schematic view illustrating two temperature sensors of atemperature control with one sensor inserted in a material being stored,here an apple, and the other sensor in contact with the surface thereof.

The container The apparatus of this invention comprises a container 10which is similar to the container disclosed in the above Fuller et al.patent and which contains circulating air passages at the sides, bottomand top similar to those disclosed in the Fuller et al. patent. Thus,the container has a false top 11 to provide an atmosphere passage 12, afalse side wall 13 to provide a side atmosphere passage 14 and a false`bottom 15 to provide a bottom atmosphere passage 16. The bottom 15 ismade up of parallel spaced coplanar supports 17 supported on parallelspaced cross supports 18 to permit atmosphere flow upwardly between thesupports 17 and 18.

The upper atmosphere passage 12 is provided with a series of blowers 19operated by motors 20. These blowers receive atmosphere from the storagespace 21 through openings shown schematically at 22. The blowers 19circulate atmosphere through the container by drawing in the atmosphereas mentioned through the openings 22 from the space 21 and blowing it tothe left, as shown in FIGURE l, through the horizontal top passage 12.From here the atmosphere is forced downwardly through the side passage14, into the bottom passage 16, upwardly between the horizontal spacedsupports 17 and back into the space 21 to complete the circuit.

The passages 12, 14 and 16 and the blowers 19 and motors 20 inapproximately one-half of the container 10 are as shown in FIGURE l.Similar elements for the other half of the container are arrangeddirectly opposite. This is illustrated more completely in theabove-mentioned Fuller et al. patent. Thus, in the side passage 23 whichis opposite to the side passage 14 ow of the atmosphere is downward ascaused by the elements of the other half of the container.

Temperature controls Located in the top atmosphere passage 12 downstreamfrom the blowers 19 is a refrigerant evaporator 24. The refrigerationsystem also includes a refrigerant compressor 25 operated by an electricmotor 26, a condenser 27, a refrigerant receiver 28, a dryer 29, anexpansion valve 30, a second expansion valve 31, a pressure regulatingvalve 32 and a blower 33 operated by a motor 34 and arranged to cool thecondenser 27 as indicated by the arrows 35.

The compressor 25 is arranged to operate substantially continuouslyunder normal conditions as it has been found that this produces bettertemperature control in the storage space 21 and avoids heavy start-uploads as is tr-ue where the temperature is controlled by cycling thecompressor on and off.

In order to provide for this substantially continuous operation of thecompressor 25 two refrigerant circuits are provided with one being usedto supply liquid refrigerant to the evaporator 24 when cooling isrequired and the other permitting circulation of the refrigerant fromand to the compressor when refrigeration is not required.

One of these refrigerant ow circuits includes a line 36 for hotrefrigerant gas from the compressor 25 to the condenser 27. From thecondenser 27 the line 36 conveys hot refrigerant liquid from thecondenser 27 to the receiver 28 and the dryer 29.

From the dryer 29 to line 36 connects to a valve 37 operated by asolenoid 38 and from there to the expansion valve 30. From the valve 30the line 36 conveys the liquid refrigerant which is now a cool liquidbecause of its passage through the expansion valve to the inlet to theevaporator 24.

The expanded refrigerant gas is conducted from the evaporator 24 througha line 39 back to an inlet to the compressor 25 by way of the pressureregulating valve 32. This regulator valve 32 maintains a constant backpressure on the evaporator 24 to keep the evaporator operating at asubstantially constant temperature.

An auxiliary line 40 is provided around the pressure regulating valve 32with this line 40 containing a valve 41 operated vby a solenoid 42.

As is obvious from the above, the lines 36 and 39 provide therefrigerant circuit through the evaporator 24 when cooling is required.

In order to provide for refrigerant ow when cooling is not required, sothat the compressor 2S may be operated substantially continuously, thereis provided a refrigerant gas line 43 leading from the line 36 upstreamof the condenser 27. This line 43 directs refrigerant through expansionvalve 31 to a coil 44 in the top atmosphere passage 12 in the container10 downstream of the blowers 19 and between these blowers and theevaporator 24. The coil 44 is located in this position so that therefrigerant gas in line 43 will be cooled by the blowers.

From the coil 44 the refrigerant is returned to the compressor 25 by wayof a line 45. Lines 39 and 45 are under the same pressure, in this casethe suction pressure of compressor 25.

When valve 37 is opened by its solenoid 38 to provide refrigeration inthe circulating atmosphere within the container the refrigerant flowsfrom the compressor through line 36 by way of the condenser 27, receiver28, dryer 29, open switch 37 and expansion valve 30 to the evaporator.The refrigerant is returns@ ,from the evaporator 24 through the line 39to the compressor 25 by way of the pressure regulating valve 32. Y

When refrigeration is not required valve 37 will be closed so that nowthe refrigerant will ilow from the compressor 25 through line 43,expansion valve 31, coil 44, line 46 back to the compressor. Theexpansion valve 30 is controlled or modulated by a conventionalthermostat 46 on the refrigerant line 39 which is a suction line leadingfrom the evaporator to the compressor.

Connected to the refrigerant outlet line 36 by way of a branch line 47is an ordinary pressure operated switch 48. This switch 48 controls theoperation of the blower motor 34, as indicated by the connecting dashline 49. Here as with the other dash lines of FIGURE 1 the elementcontrolled and the controller therefor are connected by dash lines forclarity of illustration.

If the condenser 27 is not condensing substantially all of the gaseousrefrigerant to a hot liquid, pressure will build up in the line 36. At apredetermined pressure, after startfup of compressor 25, such as about130 pounds per square inch the pressure switch 48 will close the circuitto the motor 34 to operate the blower 33 and cool the condenser by theair stream 35. When operation of compressor 25 is discontinued, or assoon as the pressure in the line 36 drops to a pressure such as about 90pounds per square inch, indicating that the refrigerant is beingcondensed to a liquid, switch 48 will open to stop operation of theblower 33.

Pressure switch 48 which as previously described controls the operationof the motor 34 of the blower 33 is in an electric line 63 which isacross electric leads N and L3 with the motor 34 and switch 48 being inseries. As is shown at the bottom of FIGURE 2, the switch 48 comprises apair of spaced contacts 64 and 65 and a movable bridging contact 66adapted to close the circuit between contacts 64 and 65. The movablecontact 66 is moved by pressure in the uid line 47 operating through abellows 67.

The solenoid 38 which as previously mentioned controls refrigerant owthrough valve 37 to the evaporator 24 is in an electric line 68connected across electric leads N and L2. The solenoid 38 is in serieswith a normally closed switch 69 and in series with a pair of normallyopen switches 70 and 71 arranged in parallel with each other.

The solenoid 42 which controls the by-pass valve 41 which permitsrefrigerant ow from the evaporator 24 to the compressor 25 to by-passthe pressure regulator valve 32, as previously described, is in anelectric line 72 that extends between the leads N and L2. In the line 72the solenoid 42 is in series with a temperature control switch 73- of awell known construction which is adjustable to actuate at a preselectedtemperature. The temperature control 73 is connected to a pair oftemperature sensors 74 and 75 whose operation will bedescribedhereinafter.

The temperature control 73 which is of usual construction includes amovable switch arm 76 that is moved into and out of engagement with afixed contact 77 by ternperature sensed by the sensors 74 and 75.1Thisrelationship is indicated by the dash line 78. Arranged in parallel withthe control switch 73 is a normally open switch'79 in its electric lead80 which has one end connected to the circuit line L2 and the other endconnected to the line 72 between the solenoid 42 and the switch 73.

As described earlier, when the evaporator 24 is operating normally tocool the space 21 in the container 10 the valve 41 is closed so that therefrigerant return line 39 from the evaporator is maintained ata'constant pressure by the pressure regulating valve 32. When it isdesired to operate the evaporator 24 at increased capacity so as toproduce a lower temperature, solenoid 42 is used to open valve 41 sothat the return refrigerant may flow without restriction into thecompressor 25 by way of the bypass line 40. The circuit to the solenoid42 is controlled by a number of controllers including the previouslydescribed temperature control 73 as is indicated by the dash line 84 ofFIGURE 1.

Temperature control 73 is adjustable and is operated by the sensor 74which is inserted in the material being stored in space 21 with theother sensor 75 contacting the surface of the article. FIGURE 4exemplifies this arrangement in an apple 85. The material such as theapple 85 with which the sensors 74 and 75 are associated shouldpreferably be located at the coldest place in the stored material. Withthis arrangement when the stored material interior temperature is abovethe temperature as set on the control 73, as when the warm harvestedmaterial is first placed in the container 10, sensor 74 activates switch76 to engage contacts 77 and energize the solenoid 42. This opens thevalve 41 to permit full flow of refrigerant into and from the compressorso that the evaporator 24 functions at a lower than normal temperatureto chill rapidly the stored material. Since the stored product underthese conditions may freeze from the outside in before the sensor 74 isactivated to close valve 41, the surface sensor 75 operates to maintaina temperature in space 21 which is the lowest value at which the productsurface will not freeze. Sensor 75 therefore controls the rapid chillingof the stored product until the temperature of the interior of thematerial being stored and the sensor 74 reaches the predeterminedtemperature as set on control 73, whereupon the switch 73 is opened tode-energize solenoid 42 and close the valve 41 whereupon therefrigeration system operates in its normal manner. This normaloperation continues until a low chilling temperature is again requiredin the storage space 21.

During normal functioning of the apparatus of this invention to storematerials as previously described, the preselected temperature withinthe space 21 is controlled by the temperature control 85 which has asensor 86. The sensor 86 is preferably located at the coldest areawithin the container and is illustrated in FIGURE 1 as at the junctionof the side atmosphere passage 14 and the bottom passage 16.

As is shown in FIGURE 2 temperature control 8S contains a movable switcharm 87 which is moved by the temperature of the sensor 86, as indicatedby the dash line 88. This temperature control switch 85 is aconventional commercially available product. The temperature sensed bythe sensor 86 moves the switch arm to engage either one contact 89 or asecond contact 90 or neither. The switch 87 is connected by an electricline 91 to the lead L1. The contact 89 is connected by a line 92 toelectric lead N and the line 92 contains a relay coil 93. The otherswitch contact 90 is similarly connected to N by a line 94 which alsocontains a relay coil 95. Relay coil 95 when energized closes thenormally open switch 70 which is in series with solenoid 38 forenergization thereof and relay coil 93 closes normally open switches 96,97 and 98 to energize reheater 99.

As is shown in FIGURE 1 the top atmosphere passage 12 contains anelectric reheater 99 and an electric reheater 100. Reheater 99 iscontrolled by the temperature control 85 as indicated by the dash line101 and reheater 100 is controlled by temperature control 85 and anexternal temperature control 103 having a temperature sensor 104 asindicated by the dash lines 105 and 102.

As shown at the top of FIGURE 2 the temperature control 103 which is astandard readily available product comprises a pair of spaced xedcontacts 106 and 107 adapted to be engaged by a movable bridging contact108 that is moved by a bellows 109 activated by the sensor 104. Theswitch 103 is in an electric line 110 across the leads N and L1 and inseries with a relay coil 111. The coil 111 is arranged to open thenormally closed switch 60 and to close the normally open switches 112,113 and 114. When switch 60 opens, relay coil 62 is de-energized openingswitches 81, 82 and 83 and de-energizing compressor motor 26. As can beseen in FIGURE 3, switch 112 is in series with reheater 100 and Withswitch 96 with this series being connected across the lines L1 and L2.Reheater 99 is also in this circuit across L1 and L2 but is in parallelwith reheater 100 and switch 112. Switch 113, reheater 100 and switch 97are also in series across lines L2 and L3 with reheater 99 also beingacross these lines but in parallel with heater 100 and switch 113.Switch 114 and reheater 100l are in parallel with reheater 99, and allare in series with switch 98, with this circuit being across the linesL1 and L3. In addition, normally open switch 115 is in parallel withswitch 112, normally open switch 116 is in parallel with switch 113 andnormally open switch 117 is in parallel with switch 114.

As explained earlier, the sensor 86 of the temperature control maintainsthe preselected temperature within the storage space 21. If sensor 86senses a lower than preselected temperature on the control 85 within thespace 21 the switch arm 87 is moved to engage contact 89 and energizerelay coil 93. This energizing of relay coil 93 closes the normally openswitches 96, 97 and 98 to energize the reheater 99 which will thenprovide heat to the circulating air stream in the manner previouslydescribed. When the storage space 21 is raised to the preselectedtemperature on the control 85 the sensor 86 moves switch arm 87 out ofengagement with contact 89 to de-energize coil 93 which permits contacts96, 97 and 98 to open and de-energize the reheater 99. When the sensor86 senses a higher than preselected temperature on the control 85 itmoves the switch arm 87 into engagement with contact to energize coil 95which closes switch 701 and energizes solenoid 38 of valve 37 to providerefrigerant tiow to evaporator 24.

The principal temperature control 85 therefore operates to supply heatto the storage space 21 when the temperature therein is too low andsupply cold when the temperature is too high. In the control 85 thecontact 90 which controls the relay provides and controls the cooling,and the contact 89 which controls the relay 93 provides and controls theheating.

As described earlier sensor 104 of temperature control 103 is locatedoutside the container to sense the ambient temperature of thesurrounding atmosphere. When the ambient temperature falls below thepreselected temperature required in the storage space 21 the sensor 104moves the bridging contact 108 into engagement with the contacts 106 and107 to energize the relay coil 111. Coil 111 thereupon opens contact 60to de-energize relay coil 62 which thereupon permits switches y81, .82and 83 to the refrigerant compressor motor 26 to open and stop thecompressor 25. This relationship of the temperature control 103 to thecompressormotor is indicated by the dash line 118. The compressor isstopped during this period as refrigeration is no longer needed due tothe low ambient temperature.

The energizing of relay coil 111 by the temperature control 103 alsocloses switches 112, 113 and 114 to place the heater in the electricalcircuit along with the reheater 99 so that both can be controlled by theswitches 96, 97 and 98 which are controlled by the main temperaturecontrol 85 and its sensor 86 as described previously.

Humidity control Located in the upper passage 12 for the circulatingatmosphere is a sensor system 119 for a humidity control 120. Both thehumidity control and its sensor are standard products that are readilyavailable commercially. Thesensor elements 255 of the sensor 119 arepositioned downstream from the heaters 99 and 100 and the evaporator 24.The sensor 119 monitors the relative humidity of the atmosphere in thepassage 12 and sends the signal to the humidity control 120 which may beadjusted to maintain any preselected relative humidity within itsoperating range.

The humidity control 120 is arranged to activate the motor 121 of an aircompressor 122 as indicated by the dash line 123. The control 120 isalso arranged to activate the solenoid 124 of a valve 125 as indicatedby the dash lines 123 and 256. The air compressor 122 is arranged todraw atmosphere from the storage space 21 through a uid line 126 or12-6a, with the line 126 containing an adsorber 127 for adsorbing carbondioxide and a two-way valve 127a for controlling the flow of atmospherefrom storage space 21 through either of lines 126 or 126a. 1f the carbondioxide level in space 21 rises above a predetermined amount, the carbondioxide control 231 will activate valve 127a to cause atmosphere to owthrough adsorber 127 to remove carbon dioxide therefrom. If the carbondioxide level in space 21 reaches or drops below a predetermined amount,the carbon dioxide control 231 will de-activate valve 127a to allowatmosphere from space 21 to bypass adsorber 127 and flow through line126. This adsorber contains nely divided activated carbon which is theadsorbing medium for removing carbon dioxide as described in Brown etal. copending application Ser. No. 213,520, led July 30, 1962', nowPatent No. 3,203,771, and assigned to the same assignee as the presentapplication.

From the compressor 122 a fluid line 128 leads to an outlet 129 in theatmosphere passage 14. Also located in this line is a pressure reliefvalve 130 that is arranged to open at a predetermined pressure such asabout 2O pounds per square inch. Connected to the fluid line 128 betweenthe compressor 122 and the valve 130 is a fluid line 131 which exhauststhrough a liquid atomizer 132 having an inlet 133 located at the bottom134 of the container 10. This bottom 134 is adapted to retain a body ofwater 135 which is initially placed there and is maintained either byadded water or by defrost water from defrosting the evaporator 24. Inany event, a sufficient level of water 135 is maintained so that theinlet 133 will draw in water for atomizing at 132 by compressedatmosphere flowing through the line 131.

If the humidity sensor 119 senses a relative humidity lower than thatset on the control 120 the control energizes solenoid 124 of valve 125and energizes motor 121 of compressor 122. The compressor thereupondraws atmosphere from the storage space 21 through the iluid line 126and adsorber 127 or fluid line 126a dependent upon the level of carbondioxide in space 21 as discussed above. In the compressor 122 theatmosphere is compressed and directed through line 131 and valve 125into the atomizer 132. Here the atmosphere tlow picks up water from thewater body 135 and distributes it into the down flowing atmospherestream in the side passage 14. This atomizing of the water into theatmosphere raises the humidity.

Humidity control 120 is provided with spaced xed contacts 139 and 140and a switch arm 136 that is movable by temperatures sensed by thesensor 119 as indicated on FIGURE 2. The contact 139 is connected by anelectric line 138 on the solenoid 124 of valve 125 and relay coil 137.The solenoid 124 and relay 137 are in parallel With each other and theseand the control 120 are connected across the circuit lines N and L1.Contact 140 of humidity control 120 is connected to circuit line N byway of line 145. Thus with this arrangement solenoid 124 and relay coils137 and 144 are connected to circuit line N while a movable contact arm136 of the control is connected to the circuit line L1.

When sensor 119 senses a low humidity condition the switch arm 136 ismoved to engage contact 139 and energize solenoid 124 and relay coil137. Relay coil 137 thereupon energizes switches 141, 142 and 143(FIGURE 3) which energizes the compressor motor 121 to operate thecompressor 122. At the same time solenoid 124 is energized to open valve125 so that the compressor atmosphere will atomize water from the body135 to raise the humidity as previously described. When the desiredhumidity is reached switch arm 136 is disengaged from contact 139,de-energizing relay coil 137 and solenoid 124 to discontinuehumidication.

When the sensor 119 of the humidity control senses a high humidity thatis greater than that set on the control 120.switch arm 136 is moved toengage contact 140. This energizes relay coil 144. Relay coil 144 closesswitch 71 to energize solenoid 38 and open valve 37 for flow ofrefrigerant into the evaporator 24. Coil 144 also closes switches 115,116 and 117 to place reheater 100 in the circuit with reheater 99. Coil144 also closes Aswitch 79 to energize solenoid 42 to open valve 41 sothat returning refrigerant may flow freely into the refrigerantcompressor 25. The opening of valves 37 and 41 therefore operates theevaporator at lower temperatures so that the excess moisture `collectsas Vfrost on the evaporator 24. When sensor 86 of control 85 senses adrop in temperature of space 21, control actuates to close s-witches 96,97 and 98 to energize reheaters 99 and 100 which are downstream from theextremely cold evaporator 24 to reheat the air from the evaporator tomaintain the predetermined storage temperature of the stored materialsduring the removal of the moisture in the form of frost. As an example,in` one embodiment of the invention the evaporator is normally operatedat about 30 F. During the extreme cooling of moisture removal theevaporator is operated at about 20 F.

When the humidity sensor of control senses a correct humidity conditionin the storage space 21, as represented by the circulating atmosphere inthe upper passage 12, switch arm 136 of humidity control 120 disengagescontact 140 to de-energize the relay coil 144. This deenergizes solenoid38 to permit refrigerant supply valve 37 to close and de-energizesolenoid 42 to permit bypass valve 41 to close so that the refrigerationapparatus now operates in the normal manner. At the same time thede-energizing of relay coil 144 opens switches 115, 116 and 117 whichde-energizes the reheater 100. The other reheater 99 remains in thecircuit and will not be deenergized until the sensor 86 of maintemperature control 85 senses the preselected temperature in space 21that is set on the control 85. The relationship of the humidity control120 to solenoids 38 and 42 is indicated on FIG- URE l by the dash lines195 and 249.

Defrost control During normal operation of the refrigeration systemyfrost tends to build up on the evaporator 24. Frost also builds up, aspreviously described, in removing excess humidity. As the frost buildsup on evaporator 24, ow of atmosphere forced therethrough by the blowers19 is restricted. This increases the atmosphere pressure on the upstreamside of the evaporator and decreases it on the downstream side. Thisdifference in pressure is used to operate automatically the defrostsystem.

A differential pressure switch 146 is provided having a static pressuresensor 147 on the upstream side and a similar sensor 148 on thedownstream side of the evaporator. These pressures are conveyed to theopposite sides of switch 146 by fluid pressure lines 149 and 150, andbellows 151 and 152, respectively.

Higher pressure in line 149 caused by increasing frost accumulationmoves a movable switch arm 153 into engagement with a fixed contact 154in the switch 146. This completes a circuit through a relay coil 155(FIG- URE 2), a high limit safety thermostat 156 onthe evaporator whichis arranged to open at about 75 F., a defrost termination thermostat 157also in the evaporator and arranged to open at about 55 F., a selectorswitch arm 158 'of a manually operated double pole double'throw switch159 and a selector switch arm 160 in this same switch. There is alsoprovided a normally open switch 161. In order to provide the powersupply fory this arrangement an electric lead 162 extends between lineL1 and switcharm 160. Another electric lead 163 extends from the otherswitch arm 158 toa line 164. Coil 155 and switches 156 and 157 are inseries in line 164. Normally open switch 161 is arranged across lines162 and 163. The side of line 164 opposite its connection to line 163 isconnected to the supply line N. To complete the circuit an electric line165 extends from the xed contact 154 to a terminal 166 on the switch159. A second terminal 167, a third terminal 168 and a fourth terminal169 are provided on the switch 159. When the jointly movable switch arms158 and 160 are in the positions shown in FIGURE 2, they engage thecontacts 166 and 168, respectively. When the switch arms are raised fromthe positions shown they engage terminals 167 and 169, respectively.

As stated above, increasing pressure caused by frost blockage of theevaporator moves switch arm 153 into engagement with switch contact 154to energize the relay coil 155. This relay coil then closes normallyopen switch 161 which then acts as a holding switch to maintain electricpower to the relay 155 and thus continues to energize it by bypassingswitch 146. This is important as it keeps relay coil 155 energized evenif switch 146 should open due to partial defrosting of the evaporator.

Energized relay coil 155 also opens normally closed switch 69 to makecertain that solenoid 38 remains deenergized even if switches 70 and 71were to be closed. This maintains valve 37 closed and blocks therefrigerant ow to the evaporator so that it cannot begin to cool duringthe defrosting operation.

The energized relay coil 155 also opens normally closed switch 171 tode-energize relay coil 172. This relay coil 172 is in series with anormally closed switch 171 and a normally closed thermostat 173 on theevaporator 24 with this series being in an electric line 174 across thesupply lines L3 and N.

The above described de-energizing of coil 172 by opening switch 171permits normally open switch 175 (which has been closed during normaloperation) to open. This switch 175 is in series with the motor 20 tothe atmosphere circulating blowers 19 and connected across supply linesL2 and N by an electric line 176. This de-energizing of blower motor 20means that atmosphere is not circulated through the storage space duringthe defrosting, eliminating unnecessary temperature rise in space 21from the preselected temperature.

The relay coil 15S energized as above described also closes normallyopen switch 177 to energize relay coil 178 which are in series with eachother across supply lines L1 and N and in electric line 179. Thisenerigizing of relay coil 178 closes normally open switches 180, 181 and182 to energize the defrost heater 183 that is located on theevaporator, as shown in FIGURE l. As is shown in FIGURE 3, switch 180 isin series in line 187 with the heater 183 across electric supply linesL1 and L3. Heater 183 is connected across these supply lines by anotherelectric line 185. Switch 181 is in series with heater 183 in line 186across supply lines L3 and L3. Switch 182 and heater 1183 are in seriesin line 185 which places them across supply lines L1 and L3. Thisenergizing of defrost heater 183 melts frost from the evaporator whichthen drops down in the form of water to replenish the body of water 135at the bottom of the container 10.

The energized relay coil 155 also opens switch 61 in order to preventenergizing of the relay coil 62 during defrosting. This de-energizing ofcoil 62 maintains switches 81, 82 and 83 to the compressor motor 26 openso that the compressor 25 cannot operate during defrosting. As is shownat the top of FIGURE 3, switch 81 is in electric line 188 extendingbetween supply line L1 and the compressor motor. Switch 82 is similarlyin line 189 extending between supply line L3 and the compressor motor.Switch 83 is in line 190 connecting supply line L3 and the compressormotor 26.

After the frost has been melted from the evaporator as described abovethe temperature on the evaporator rises to a point such as about 53 F.indicating that defrosting is complete. At this point the terminationthermostat 157 on the evaporator opens to de-energize the relay coil andpermit the normally open switches 161 and 177 to open. Switch 161 opensthe circuit 164 and permits the pressure operated switch 146 to takecontrol through the electric lines 162 and 163. Because the frost hasnow been removed so that pressures on opposite sides of the evaporator24 are normal fluid pressure in the bellows 152 acting against the uidpressure in the bellows 151 moves the switch arm 153 away from itscontact 154. This returns the control to its normal condition.

The de-energizing of coil 155 as described also opens switch 177 andthereby de-energizes coil 178. The de-energizing of coil 178 permitsswitches 180, 181 and 182 to open, thereby breaking the circuit to thedefrost heater 183.

The de-energizing of coil 155 closes switches 61, 69 and 171. Thisclosing of switch 61 energizes coil 62 which closes the normally opencompressor switches 81, 82 and 83 to again start the operation of thecompressor. The closing of switch 69 subjects solenoid 38 of refrigerantsupply valve 37 to the control of switch 70 of the main temperaturecontrol 85 and the switch 71 which is controlled by the humidity control120, Switches 70 and 7 las shown in FIGURE 2 are in parallel with eachother and in series with solenoid 38 and switch 69 in the line 68.

Thermostat 173 located on the evaporator 24 is in series with normallyclosed switch 171 and relay coil 172 in line 174. Because of the initialhigh temperature of the evaporator during and immediately followingdefrosting switch 173 is open to de-energize relay coil 172. Thiscondition is maintained until the evaporator is chilled by therefrigerant to a predetermined low temperature such as about 38 F. Whenthis occurs switch 173 closes to again energize relay coil 172. As soonas relay coil 172 is thusly energized it closes the normally open switch175 in the line 176 to energize the motors 20 which operate theatmosphere circulating blowers 19 in order to begin circulation of theatmosphere through the storage space 21 as previously described. Thisdelay prevents the blowers 19 from operating until the evaporator is atthe preselected desired low temperature. Therefore, heat from thedefrost heater 183 is not circulated into the storage space 21 where itwould warm the stored material therein.

Instead of an automatic defrosting system as described a timer operatedsystem can be used if desired. As is shown at the top of FIGURE 2 thetimer 196 uses a motor 197 connected across supply lines N and L1 by anelectric line 202. The motor 197 operates a cam 198 which moves acontact arm 199 into engagement with a xed contact 200 on the timer,Before this occurs the switch arms 156 and 160 of manually operatedswitch 159 have been moved into engagement with switch contacts 16.9 and167 as described earlier. This results in the defrosting beingcontrolled by the timer 196 and not by the atmosphere pressures onopposite sides of the evaporator 24 as described earlier.

Oxygen control The amount of oxygen within the container 10 iscontrolled by an oxygen controller 204 having a sensor 203, illustratedin FIGURE 1, at the junction of the top passage 12 and side passage 14of the atmosphere circuit within the container 10. Oxygen sensor 203 isa conventional device such as Beckman Model 764, which senses the oxygenlevel in the container 10 and actuates the Control 204. This also is aconventional control such as Minneapolis-Honeywell Model R7 l 6 l.

Oxygen control 204 as shown at the top of FIGURE 3 is arranged toenergize a solenoid 205 of valve 206 'when the oxygen level in thecontainer is higher than that set on the control 204. This opening ofvalve 206 permits storage atmosphere which is normally low in oxygen, as

explained in the above-mentioned Bedrosian et al. patent, to ow from ahigh pressure container 207 through a supply line 208 into the sideatmosphere passage 14 for mingling with the atmosphere that iscirculated therethrough. This supplying of atmosphere dilutes the oxygenin the container 10.

The oxygen control 204 includes a movable switch arm 209 that is movedin engagement with xed contact 210 when the oxygen level is thus higherthan that set on the control 204. The circuit to the solenoid 205 isthen cornpleted between supply lines L1 and N by an electric line 211 tothe switch arm 209 and a line 213 to the fixed contact 210, in which thesolenoid 205 is located.

The oxygen control 204 has a second fixed Contact 212. A solenoid '214which controls valve 215 is in line 216, one end of which is connectedto contact 212 and the other end to supply line N. In parallel with thesolenoid 214, in line 216, is a relay coil 217 in electric line 218 alsoextending between the contact 212 and the supply line N.

If the oxygen level becomes too low in the container the sensor 203 ofthe control 204 causes movable switch ar-m 209 to move away from contact210 and engage contact 212. This energizes the solenoid 214 to openvalve 215 and also energizes relay coil 217. The energizing of coil 217closes the normally open switch 218a which is in series with motor 219to an air compressor 220 in an electric line 221 which extends betweensupply lines N and L3. This energizing of compressor motor 219 of theair compressor 220 causes the air compressor to draw air in through anair line 222 and exhaust it into the container 10 by way of a fluid line223, the open valve 21S and a uid line 224, all as shown in FIGURE 1. Asa safety feature there is provided a pressure relief valve 225 set toopen at a predetermined pressure such as about live pounds per squareinch to permit the compressed air to escape through air line 226 inwhich the relief valve 225 is located.

When the sensor 203 of the oxygen control 204 senses a correct oxygenlevel in the storage space 21, as preselected on the oxygen control 204,the sensor 203 moves the switch arm 209 to a neutral position out ofengagement with electric contacts 210 or 212. This de-energizessolenoids 205 and 214 as well as relay coil 217 which permits switch 218to open and stop the operation of the motor 219 which drives the aircompressor 220.

The relationship of the oxygen control 204 to the solenoid 20S isindicated by the dash line 227 of FIGURE 1. The relationship of thisoxygen control to the air compressor motor 219 is indicated by the dashlines 227 and 228. The relationship of the oxygen control to thesolenoid 214 is indicated by the dash lines 227, 228 and 229.

The carbon dioxide control The carbon dioxide as well as the oxygen inthe storage space 21 of the container 10 can vary from the preselectedamounts. The carbon dioxide content is sensed Aby a sensor 230 of acarbon dioxide control 231 with the sensor 230 being located in the sidepassage 14 through which the atmosphere is passed during the circulationof the atmosphere Within the space 21. The sensor 230 is a conventionaldevice of which one example is a Model 200 infrared analyzer made byMine Safety Appliances Co. This sensor monitors the carbon dioxide levelin the container 10. The control 231 which is activated by the sensor230 is also a conventional device of which one example is aMinneapolis-Honeywell Versatran controller.

As is shown in FIGURE 3 the carbon dioxide controller 231 includes amovable switch arm 232 which is moved by signals from the sensor 230.The arm 232 is moved by sensor 230 between spaced ixed contacts 233 and234 of the control 231. The contact 233 is connected to a relay coil 235and from there to electric supply line N by way of electric line 237.Fixed contact 234 is connected to a l2 solenoid 236 and then to line Nby an electric line 238. To complete the circuit the movable switch arm232 is connected by line 239 to electric inlet line L1.

The relay coil 235 when energized closes normally open switches 240, 241and 242 to energize the motor 121 of the previously mentioned motordriven fluid compressor 122. Solenoid 236 when energized opens valve 243which permits carbon dioxide from a high pressure container 244 to flowthrough a fluid line 245 into the side passage 14 of the container 10 toadd this carbon dioxide to the atmosphere within the storage space 21.

When the sensor 230 senses a carbon dioxide content in the space 21 thatis higher than that set on the control 231 the sensor moves the switcharm 232 into engagement with contact 233 as shown in FIGURE 3. Thisenergizes relay coil 235 and closes the normally open contacts 240, 241and 242 to energize the motor 121 to the compressor 122. Theenergization of relay coil 235 also closes contacts 235a which energizessolenoid 127b which in turn actuates valve 127 a. The compressor thenoperates to draw atmosphere from the space 21 through the line 126,carbon dioxide adsorber 137 and valve 127a into the compressor 122. Theatmosphere passing through the adsorber is reduced in carbon dioxidecontent in the manner previously described. The atmosphere is thenreturned by the compressor 122 through line 128 and pressure reliefvalve 130 to the side atmosphere passage 14 for return to the stor agespace 21.

When the carbon dioxide content in the storage space 21 has been reducedto the level preselected on the controller 231 the sensor 230 moves theswitch arm 232 out of engagement with the fixed contact 233 tode-energize the relay 205, permit the switches 240, 241 and 242 to openand thereby de-energize the motor 121 to the compressor 122.

When the sensor 230 senses a lower level of carbon dioxide in the space21 than that set on the controller 231, the switch arm 232 is moved intoengagement with contact 234 to energize the solenoid 236. This opens thevalve 243 and permits carbon dioxide to flow from the high pressurecontainer 244 through the line 245 into the side passage 14 for flowinto the storage space 21. As soon as the sensor 230 senses thepreselected level of carbon dioxide in the storage space, the sensormoves the switch arm 232 out of engagement with the contact 234 todeenergize the solenoid 236 and permit the valve 243 to close.

As indicated earlier, the electrical associations of the various unitsof this apparatus are indicated by broken lines. Thus, line 191indicates the relationship of the safety thermostat 156 and the solenoid38. for the valve 37. Line 192 indicates the relationship between thedefrost termination switch 157 and the differential pressure switch 146.Broken line 193 indicates the association of thermostat 173 and theabove line 191. Broken line 194 indicates the association of the blowermotor 20 and the above line 191.

In a similar manner, broken line 201 indicates the association of timer196 and line 191. Broken line 246 shows the relationship between thecarbon dioxide control 231 and the solenoid 236 of carbon dioxide valve243. Broken line 247 shows the relationship between theA motor 121 ofthe compressor 122 and the carbon dioxide control 231. Broken line 248indicates the relationship between temperature control and broken line195 which extends between the humidity control and the solenoid 3 tovalve 37. l

Operation The operation of the individual components and circuit hasalready been described. A summary of the operation of the completeapparatus is as follows:

During normal operation of the apparatus of this invention the motordriven blowers 19 circulate atmosphere 13 in a counterclockwisedirection, as viewed in FIGURE 1, through the top passage 12, sidepassage 14, bottom pas sage 16, upwardly through the storage space 21and back to the blowers 19. The other half of the container providesatmosphere circulation in the opposite direction.

The circulating atmosphere stream is chilled by flow through theevaporator 24 in the upper passage 12. The temperature within thecontainer 21 is controlled to a temperature preselected on the maintemperature controller 85 as sensed by its sensor 86. When cooling isrequired the sensor as indicated by the dash line 238 joined to dashline 195 opens solenoid valve 37 to permit liquid refrigerant to Howfrom the refrigerant compressor 25 by way of the condenser 27, receiver28, dryer 29 and expansion valve 30 into the evaporator. Refrigerant isreturned from the evaporator by way of line 39 and pressure regulatingvalve 32 to complete this circuit.

For efiiciency of operation and to reduce the load of start-up on thecompressor a separate refrigerant path is provided when the valve 37 isclosed during periods when no cooling is required. In this second pathrefrigerant flows from the compressor 25 through a line 43 and a coil 44and back to the compressor through a line 45. The coil 44 is located inthe air stream from the blowers 19 so as to cool the refrigerant andreturn it as a cool gas to the compressor.

The main temperature control for the storage space 21 is provided by thecontrol 85. However, the temperature within the space 21 can also becontrolled by the stored material itself which is especially importantfor fast chilling of warm newly stored products. As exemplified inFIGURE 4 this is achieved by employing two temperature sensors 74 and75, one of which is inserted into the material, such as an apple 85, andthe other of which is located on the outer surface of the material.These sensors 74 and 75 operate through a temperature control 73 whichprovides fast chilling. When the temperature of the stored material isabove that set on the control 73 the control operates solenoid valve 37,as indicated by the dash line 249, to permit ilow of liquid refrigerantto the evaporator 24. At the same time control 73 opens solenoid valve41, as indicated by the dash line 84, to permit free flow of refrigerantfrom the evaporator 24 into the compressor 25, thereby bypassingpressure regulating valve 32. This provides increased flow of liquidrefrigerant to the evaporator 24 so that it operates at a subnormaltemperature for rapid chilling. The positioning of the temperaturesensor 75 on the outer surface of the apple 85 or other materialregulates the temperature control 73 to prevent freezing of the materialfrom the outside in. As soon as the temperature reaching the insertedsensor 74 is the same as that set on the control 73, control 73de-energizes solenoids 38 and 42 and returns the temperature control tothe main temperature controller 85.

In addition the external ambient air temperature must be taken intoconsideration as when it is lower than the temperature within space 21it will affect the temperature within the storage space 21. This isachieved by providing external temperature control 103 which isactivated by its sensor 105.

When the external temperature becomes abnormally low as preselected onthe control 103, the control 103 deenergizes the compressor motor 26 tostop the compressor (one of the few times the compressor is stopped) andcloses switches 112, 113 and 114 to place reheater 100 in`the electricalcircuit along with reheater 99 so that temperature control 85 canmaintain the desired temperature of the atmosphere in the storage space21. As soon as the external temperature rises above the temperature seton the control 103 (temperature set on control 103 is the same as set oncontrol 85) the compressor motor 26 is re-energized and switches 112,113 and 114 are opened, de-energizing reheater 100.

The apparatus of this invention also provides means for automaticallymaintaining a preset humidity in the atmosphere. When the humidityexceeds that preselected on the adjustable humidity controller as sensedby the sensor 119, the evaporator 24 is operated at increased capacityas previously described by opening the refrigerant supply solenoid valve37 and opening the bypass solenoid valve 41 tov permit free iiow ofrefrigerant into the compressor 25 and thus into the evaporator 24. Theexcess moisture is then deposited as frost on the evaporator 24. Thetemperature in space 21 is maintained during humidiiication byactivating reheaters 99 and 100 and controlling the output of thesereheaters by control 85.

As soon as the humidity in the space 21 reaches the pre-set value thehumidity control 120 de-energizes solenoids 38 and 42 to retum thesystem to normal operation.

When the humidity sensed by the sensors 119 is less than thatpreselceted, the control 120 activates compressor 122 to draw atmospherefrom the space 21 by way of fluid line 12611 and valve 127a to compressit and re-inject it by way of line 131 through the atomzer nozzle 132.The atomizer nozzle, operating on the Venturi principle, sucks up waterfrom the body of water 135 on the bottom of the container 10 andprojects it into the circulating atmosphere stream. In order to achievethis, of course, the humidity control 120 has also energized thesolenoid 124 to open the valve which provides access to the compressedatmosphere line 131. The atmosphere ows through this line rather thanline 128 because of the pressure relief valve 130 located in line 128.

The evaporator 24 may be defrosted either automatically or by timer 196.When the automatic defrost is used the pressure drop of atmosphereforced through the evaporator 24 by the blowers 19 is used to activatethe switch 146. This switch de-energizes solenoid 38 to closerefrigerant supply valves 37 and prevent refrigerant flow to theevaporator. It also de-energizes blower motors 20 to stop the blowers.At the same time it energizes the defrost heaters 183 on the evaporatorto melt the frost and permit the resulting water to flow down into thebody of water at the bottom of the container 10. As soon as thedefrosting is terminated the heater 183 is de-energized and the motors20 of the blowers are energized and the refrigeration system is returnedto normal operation.

Instead of automatic defrosting as described which is controlled byfrost build-up on the evaporator the defrosting may be accomplished inthe customary manner by a timer 196. With the timer the evaporator isdefrosted periodically at fixed intervals.

As stated earlier, the storage space 21 is maintained under preselectedconstant oxygen and carbon dioxide contents. The oxygen content iscontrolled by an oxygen controller 204. This controller is activated bythe oxygen sensor 203 which is inside the container 10.

When the amount of oxygen in the container 10 is in excess of thatpreset on the controller 204 this controller energizes solenoid 205 toopen valve 206 and permit oxygen poor atmosphere to tlow from highpressure container 27 into the storage container 10.

When the sensor 203 senses an insuliicient amount of oxygen in thestorage atmosphere the controller 204 activates the motor 219 of the aircompressor 220 to provide compressed air to the storage container 10.

The carbon dioxide content in the storage atmosphere is sensed by thesensor 230 which governs the operation of the carbon dioxide control231. When there is insufiicient carbon dioxide in the atmosphere,control 231 o pens solenoid valve 243 to permit carbon dioxide to flowfrom the high pressure container 244 into the storage container 10. Whenthere is excess carbon dioxide in the storage atmosphere, the control231 energizes the compressor motor 121 to operate the compressor 122.This compressor draws storage atmosphere by way of uid line 126 throughthe carbon dioxide adsorber 127 where carbon dioxide is removed. Thecompressed carbon dioxide poor atmosphere is then returned to thestorage container by way of the line 128 and the pressure relief valve130.

When the oxygen and carbon dioxide contents are those set on thecontrollers each controller is de-activated.

The apparatus of this invention provides means for adjusting the oxygenand carbon dioxide levels to maintain pre-selected conditions. Theoxygen level sometimes gets too high because when the container is firstloaded air of course enters and normal air contains about 21% oxygen.The oxygen level sometimes gets too low because oxygen is consumed bythe stored materials as explained by the above respiratory changeequation. Similarly, carbon dioxide sometimes gets too concentrated inthe storage space because carbon dioxide is given off by the materialsduring the storage time. Carbon dioxide also occasionally gets too low,such as when the container is opened either for loading fresh materialor removing a portion of the stored material as this permits the entryof air which normally contains only about 0.03% carbon dioxide.

Although the illustrative embodiment shows refrigeration, the storedmaterials may be maintained at a ternperature that is either ambient orbelow or above ambient depending on many factors such as the length ofthe storage time, the type and source of materials being stored and thenature of the material itself. A practical but not excluding limit oftemperature is about 29-120a F. Maintenance of the storage temperaturemay, in certain instances, require heating means as shown in order tomaintain even the minimum temperature if the surrounding ambienttemperature should be too low. For storing plant and animal materialssuch as fresh foods, a storage temperature of about 29-55 F. ispreferred.

The preferred amount of oxygen in the storage atmosphere is maintainedbetween approximately 1% and by volume of the atmosphere and the amountof carbon dioxide is maintained from approximately 0.5 to 6 times theamount by volume of the oxygen with the remainder of the-atmospherebeing a gas such as nitrogen from the air supply that is inert to thestored materials and which therefore has no measurable chemical eifecton the materials. ln most instances, the amount of carbon dioxide ispreferably between about 1% and by volume when the amount of oxygen isbetween about 1% and 10% by volume. For example, an atmosphere that hasbeen found to be eective for most storage under the conditions of thisinvention is one containing 4% oxygen, 10% carbon dioxide and 86%nitrogen. Some materials such as certain fruits may be better stored inan atmosphere containing 3% oxygen, 2% carbon dioxide and 95% inertgases, while other fruits may require for best results a storageatmosphere of 1% oxygen, 5% carbon dioxide and '94% inert gases. Ofcourse, it is most important that the atmosphere, regardless of itsactual gas content, is vented from the storage space during the time thepreserving atmosphere is being supplied, so that the incoming atmospheresubstantially continually replenishes the atmosphere within the space sothat the atmosphere is not static.

The continual replenishing of the atmosphere within the storage space isnecessary in order to remove respiration products as Well as otherproducts of aging. It has been discovered that if these productsresulting from the storage in the atmosphere of this invention are notremoved damage to the stored materials frequently occurs. Furthermore,by subjecting the stored materials to optimum conditions which includesthe continual replenishing of the storage atmosphere, the appearance andquality of the stored materials may be maintained at desirable levelsthroughout the storage period. This continual replenishing may beachieved by venting the atmoshpere from the storage chamber as freshatmosphere is introduced.

Although no means are shown for venting storage atmosphere from thecontainer, venting can occur from the usual leakages around sealinggaskets and through screw holes, bolt holes and other normal sources.This is explained in the above-mentioned Bedrosian et al. patent.

Most animal and plant materials will be stored at l00% relativehumidity. With some materials such as onions, grains and nuts thehumidity may be lower such as that of ambient conditions. Thus, therelative humidity may be as loW as 25% or lower and as high as 100%.

Examples of animal and plant materials that may be stored for longperiods of time under the conditions of this invention are non-foodmaterials such as cut owers, tobacco, flower bulbs and the like andfoods such as apples, berries, peaches, pears, milk products includingmilk, butter and cheese, onions, celery, tomatoes, carrots, oranges,meat and meat products, eggs, potatoes, bananas, grapes, asparagus,beans, grains, nuts, peas and the like.

Having described our invention as related to the ernbodiment shown inthe accompanying drawings, it is our intention that the invention be notlimited by any of the details of description, unless otherwisespecified, but rather be construed broadly within its spirit and scopeas set out in the accompanying claims.

The embodiment of the invention in which an exclusive property orprivilege is claimed is defined as follows:

1. Apparatus for storing for a storage period perishable animal andplant materials subject to respiratory de'- terioration changes onstorage in air containing normal quantities of oxygen and carbon dioxidewherein oxygen is consumed and carbon dioxide is produced according tothe following approximate respiratory change equation:

wherein (CHZO)n represents a carbohydrate molecule from said materials,comprising: means forming an enclosure having a storage space for saidmaterials; means for maintaining in said storage space during saidperiod a storage atmosphere containing oxygen and carbon dioxide, theamount of oxygen being less than said normal air quantity and the amountof carbon dioxide being greater than said normal air quantity, to retardbut not prevent the progress of said equation; means for withdrawingfrom said storage space and then returning to said storage space aportion of said storage atmosphere by way of an atmosphere conduitleading from said storage space and returning to said storage space;means for selectively directing said portion from said conduit throughan auxiliary conduit to said storage space; means for utilizing saidportion in said auxiliary conduit for introducing an added ingredient tosaid storage space; means including a iiuid compressor in saidatmosphere conduit for said withdrawing from said storage space and thenreturning to said storage space said portion of said storage atmosphere;carbon dioxide sorption means in said atmosphere conduit for removingcarbon dioxide; a source of water; means forming an exit from saidauxiliary conduit to said storage space; an injection nozzle at saidexit having an inlet in said Water source for injecting moisture intoSaid storage space with compressed storage atmosphere from saidauxiliary conduit; and means for selectively diverting said portionthrough said auxiliary conduit to introduce moisture to said storagespace.

2. The apparatus of claim 1 wherein said means for selectively divertingcomprises valve means, and there are provided carbon dioxide detectionmeans in communication with said storage space for detecting the amountof carbon dioxide therein, means activated by said detection means whenthe carbon dioxide in said space exceeds a preselected concentration foroperating said fluid compressor to withdraw said portion through saidconduit and said sorption means and return said portion with its reducedcarbon dioxide content to said storage space,

17 means for terminating said uid compressor means operation when thecarbon dioxide in said storage space is at a preselected concentration,humidity detection means in communication with said space, moisturesupply means operated by said humidity detection means when humidity insaid space drops to a preselected level for simultaneously operatingsaid uid compressor to withdraw said portion through said conduit andopening said valve to direct said storage atmosphere portion throughsaid auxiliary conduit to introduce moisture to said storage space, 10

References Cited UNITED STATES PATENTS 2,214,264 9/1940 White 99-2712,353,538 7/1944 Barber.

2,923,629 2/1960 Bonomi.

3,107,171 10/1963 Robinson 99154 3,313,630 4/1967 Harvey 99-150 JAMES H.TAYMAN, JR., Primary Examiner U.S. Cl. X.R.

